Antidiarrheals

Types and differences of antidiarrheals

The major medications used as antidiarrheals include:

In some cases, drugs such as opioids and codeine may be prescribed to treat diarrhea.

Conditions of concern

Before taking antidiarrheals, patients should inform their physician if they have a fever or mucus or blood in their stools. In addition, patients with a history of liver or kidney disease may not be good candidates for antidiarrheals.

Patients who have any of the following conditions may not be good candidates for treatment with the antidiarrheal medicine bismuth subsalicylate:

• Stomach ulcer. Ulcer or open sore in the lining of the stomach.
• Dysentery. Infection of the colon characterized by severe, bloody diarrhea.
• Gout. Painful form of arthritis that usually affects single joints, most often in the feet.
• Hemophilia. Disorder that causes clotting problems or other bleeding problems.

Patients with colitis or dysentery may not be good candidates for treatment with loperamide.

Psyllium and methylcellulose should not be taken by patients experiencing abdominal pain, nausea or vomiting. Patients should also avoid these drugs if they have signs of appendicitis, intestinal obstruction or ulceration, or swallowing difficulties. Diphenoxylate should not be used by patients who have certain types of diarrhea and patients with narcotic dependence or acute ulcerative colitis.

Potential side effects

Side effects associated with the antidiarrheal medication bismuth subsalicylate are rare, although some patients may experience a darkish tongue or grayish-black stools until they stop taking the medication. Patients who use bismuth subsalicylate should notify a physician if they experience any of the following:

• Severe constipation
• Severe or continuing diarrhea
• Severe or continuing nausea and vomiting
• Severe or continuing stomach pain
• Anxiety
• Loss of hearing
• Confusion
• Difficulty speaking or slurred speech
• Dizziness or lightheadedness
• Severe drowsiness
• Fast or deep breathing
• Severe or continuing headache
• Increased sweating
• Increased thirst
• Mental depression
• Muscle spasms, particularly in the face, neck and back
• Muscle weakness
• Ringing or buzzing in the ears
• Trembling
• Uncontrollable flapping movements of the hands (especially in elderly patients)
• Other uncontrolled body movements
• Vision problems

Side effects are also rare in those using loperamide, although patients may experience dryness of mouth, dizziness or drowsiness. However, patients who are taking loperamide should consult a physician if they experience any of the following side effects:

• Bloating
• Constipation
• Severe stomach pain with nausea and vomiting
• Loss of appetite
• Skin rash

Other side effects associated with antidiarrheals include:

• Abdominal cramps
• Central nervous system (CNS) effects such as drowsiness and headache
• Rapid heart rate (tachycardia)
• Prolonged dilation of the pupil (mydriasis)
• Dry mouth
• Urine retention
• Skin itchiness or rash

Drug or other interactions

Patients who are candidates for taking bismuth subsalicylate should inform their physician of any history of unusual or allergic reaction to any salicylates, including aspirin. Patients taking either bismuth subsalicylate or loperamide should report all other allergies, including those to foods, preservatives or dyes, to their physician.

Use of bismuth subsalicylate may cause increased bleeding in patients who use anticoagulants (medications that help prevent the blood from clotting). Patients who take oral antidiabetic medications may find that bismuth subsalicylate causes blood sugar levels to fall too low. Patients who take any pain medicines or anti-inflammatory medicines that contain salicylates may experience increased incidences of side effects associated with those drugs. Bismuth subsalicylate may also hamper the effectiveness of antibiotics such as tetracyclines.

Medicines that may interact poorly with bismuth subsalicylate include the gout medications probenecid and sulfinpyrazone. Other drugs that may interact poorly with bismuth subsalicylate include the following analgesic, anti-inflammatory, anti-arthritic or antipyretic medications:

• Diclofenac
• Diflunisal
• Fenoprofen
• Flurbiprofen
• Ibuprofen
• Indomethacin
• Ketoprofen
• Naproxen
• Piroxicam
• Sulindac
• Suprofen

Patients who use loperamide may be at risk for severe constipation if they are also taking narcotic pain medicine. In addition, loperamide can worsen diarrhea caused by taking certain antibiotics such as erythromycins and tetracyclines.

Patients taking diphenoxylate should avoid using central nervous system (CNS) depressants (including alcohol and tranquilizers) and antidepressants such as MAO inhibitors. Both psyllium and methylcellulose can absorb other medications that are taken by the patient, blunting the effectiveness of these drugs.

Pregnancy use issues

Women who are pregnant, thinking of becoming pregnant or breastfeeding should not use antidiarrheals without first consulting a physician. Salicylates such as bismuth subsalicylate have not been shown to cause birth defects in humans, but are known to cause birth defects in animals. In addition, studies have shown that use of salicylates late in pregnancy may have undesirable effects on a newborn infant’s heart or blood flow. Use of salicylates during the final two weeks of pregnancy may cause bleeding problems in the fetus before or during delivery, whereas excessive use of salicylates during the last three months of pregnancy may result in a variety of problems for the mother. These include extended pregnancy, prolonged labor and severe bleeding before, during or following delivery.

It is not known how loperamide might affect pregnant women and their babies, although animal studies have not shown the drug to cause birth defects.

Salicylates pass into breast milk, although they do not appear to cause problems in nursing babies when taken by the mother in modest amounts. It is not known whether or not loperamide passes into breast milk.

Child use issues

Children younger than age 12 who have significant diarrhea should not use bismuth subsalicylate, and children under age 6 should not use loperamide. Instead, children under these ages who experience persistent diarrhea should be taken to a physician for medical care. Children with viral infections such as chickenpox or influenza should not take bismuth subsalicylate because of an increased risk of developing Reye syndrome, a condition in children associated with the use of aspirin and other salicylates that results in brain and liver damage.

Fluid loss caused by diarrhea can present serious health risks in children, and antidiarrheals can sometimes mask this dehydration. Fluids, including oral electrolyte solutions, can prevent dehydration. Older children with diarrhea may use antidiarrheals, but it is important that they also receive sufficient fluids to prevent dehydration.

Children who take antidiarrheals may be more sensitive to side effects than adults, especially if they have a fever or have lost large amounts of body fluid through vomiting, diarrhea or perspiration. The bismuth that is present in bismuth subsalicylate may also cause constipation in children.

Elderly use issues

Elderly patients should not take antidiarrheals without first consulting a physician because fluid loss associated with diarrhea may result in severe health problems. As with children, it is vital that elderly patients maintain a proper fluid level to avoid dehydration.

Elderly patients are more likely to suffer side effects associated with antidiarrheals than younger adults. The bismuth in bismuth subsalicylate may cause constipation in older individuals.